Forms :: Subform - Input Box Reappears When Closing Database

I have a

- form called "Hauptformular" and a
- subform called "qry_tracking_Unterformular". Then there is a
- button called "cb_filialname".

Now when opening the Database, the form appears with the subform containing the
- query "qry_tracking"

When hitting the button "cb_filialname" the subform receives the contents of the
- query "qry_tracking_FilName", that has a filtering option on the Column "Filiale": "Like [Filialname?]"

Now the filtering works fine with the following Code:

PHP Code:

Private Sub cb_filialname_Click()Me!qry_Tracking_Unterformular.Form.FilterOn = 
FalseMe!qry_Tracking_Unterformular.Form.RecordSource = "qry_tracking_FilName"End Sub 

-> when you hit the button, the inputbox

Filialname?

appears.

The problem now is, that after having used the button, when I click the "Exit" cross right up there, the inputbox appears again.